In general, front structures of a vehicle body are formed with at least one ring-shaped or quadrangle frame to cope with a transverse load generated when the vehicle corners and the accompanying torsion or bending and to satisfy crash-related marketability standards which are being strengthened.
Diverse connection structures for forming the ring-shaped or quadrangle frames are being applied to commercial vehicles. For example, there is the ring-shaped (or quadrangle) structure of front sub-frame, and the ring-shaped (or quadrangle) structure formed by connection of left/right front side members, dash cross member, and a back beam of a front of a vehicle body is also a same kind.
FIG. 1 is a perspective view of a connection structure of a vehicle in the related art.
FIG. 3 is a cross-sectional view for showing details of a connection structure of a vehicle in the related art.
Referring to FIG. 1 and FIG. 3, the ring-shaped (or quadrangle) structure formed by connection of left/right front side members 20, a dash cross member 60, and a back beam 50 is shown in a related art connection structure of a vehicle.
In related art, a fender apron upper 10 is coupled to a middle portion of a front side member 20 in a length direction thereof by a fender apron front lower reinforcement 11.
Only a rear member in a length direction of a vehicle in a ring-shaped structure of a front sub-frame 70 is shown in FIG. 1, because a front member of the front sub-frame 70 and a front member of the front side member 20 are not coupled.
Referring to FIG. 3, details of a related art connection structure of a vehicle are illustrated.
Referring to a cross section A-A of FIG. 3, both ends of a fender apron front lower reinforcement 11 and a fender apron inner front 12 are respectively coupled to a fender apron upper 10 and a front side member 20 such that the fender apron upper 10 and the front side member 20 are connected.
Particularly, a front side member 20 and a fender apron front lower reinforcement 11 or a fender apron inner front 12 are coupled at contacting surfaces substantially perpendicular to a width direction of a vehicle.
Therefore, fractures of the contacting surfaces can easily happen by shear load when colliding because only one kind of faces almost perpendicular to the width direction of the vehicle are coupled in a connection structure of a fender apron upper 10 and a front side member 20.
A crash barrier may destroy a vehicle body and intrude inside the body. In case of a small overlap crash, and thereby a transverse behavior of the vehicle is almost not generated. Accordingly, almost 100% of crash energy is transmitted to the vehicle body.
This kind of a connection structure is especially dangerous, because the crash energy is not distributed to different members of the vehicle body and is concentrated to a front side member 20.
This can cause a severe injury or a death of occupants.
Therefore, it is generally the case to cope with an accident of a small overlap crash by adding a reinforcement member or a plurality thereof to a transfer path of crash energy.
In addition, transverse stiffness of an engine room is not secured enough because the front member of the front sub-frame 70 and the front member of the front side member 20 are not well connected to each other.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.